Structural, high strength uranium alloys



United States tent 3,266,890 STRUCTURAL, HIGH STRENGTH URANIUM ALLOYS Jacob Greenspan, Newton, and Fortunate J. Rizzitano, Needham, Mass., assignors to the United States of America as represented by the Secretary of the Army No Drawing. Filed Mar. 23,. 1964, Ser. No. 354,180 4 Claims. (Cl. 75-122.7)

mechanical property values will be governed by their thermal history as evidenced by the data hereinafter shown in Table III.

The subject alloys are amenable to fabrication generally by well established metal working and machining methods. For example, these alloys may be formed by melting in a high frequency induction furnace under a vacuum and worked by conventional methods of hot extrusion. All heat treating was accomplished in a vacuum by conventional techniques. Likewise all machining was accomplished by conventional methods of milling, grinding, and/or lathe turning.

The range of the content of each element is listed in the following table and it should be noted that the content of each element is to be neither more nor less than that listed.

TABLE I.-CODE TO COMPOSITION, TABLES II AND III An object of this invention is to provide high density alloys with relatively superior mechanical properties, such alloys being intended generally for nonnuclear applications, where, in addition to high density, certain structural requirements must be satisfied.

Another object of this invention is to define a series of uranium alloys, in terms of a specific group of elements,and further in terms of the narrow range of each element, so that these'alloys will exhibit the mechanical and physical properties shown hereinafter in Tables 11 and III.

Still another object of this invention is to define the above stated series of alloys further in terms of their response to thermal treatment in such a manner that the Any trace elements that may be present are considered to be inadvertent impurities, and the total content should not exceed 0.1% by weight with the exception that the carbon content should be less than .02%.

Experiment showsthat the uranium alloys defined herein provide a level and range of mechanical properties, particularly in strength and hardness, not heretofore achieved in uranium alloys. It is shown further, within the said group of alloys, that the important engineering properties related to inherent ductility, such as percent elongation, percent reduction in area, and impact resistance, can be engineered to relatively useful levels by means of thermal treatment and/ or alloy content variation, as evidenced by the information obtained in the following tables:

TABLE II Composition Property (As Extruded Condition) A B C D E Tensile:

Yield Strength, 1% Offset, psi... 174, 000 183, 000 240, 000 156, 000 134, 000 190, 000 186, 000 264, 000 162, 000 140, C00 Yield Strength, 2% offset, psi... 204, 000 220,000 272,000 182,000 156, 000 222,000 222, 000 284, 000 187, 000 164, 000 Ultimate Strength, Englneering,

p.s.i "236, 000 260, 000 304, 000 250, 000 232, 000 248, 000 266, 600 312, 000 254, 000 244, 000 Elongation, Percent 2-3 2-3 1-3 6-7 5-10 Reduction, Percent 8-10 8-10 2-11 17-27 9-24 Impact Resistance, Charpy at 0 F., ft.-lbs 3-3. 4 3-3. 4 3. 4-4 3. 4-4. 0 3. 4-4 Hardness, Rockwell C 48-49 50-51 55-57 47-49 46-47 Density, gin/cm. 17. 2 17. 3 17. 6 17.8 17.9

TABLE IIL-SELECTED MECHANICAL PROPERTIES (AVERAGE VALUES) LISTED IN ACCORDANCE WITH THERMAL HISTORY FOR SUBJECT ALLO YS Composition and Thermal History Property (Thermal History as Heat Given) Treat A B C D E Tensile Yield, 1% p.s.i a 27,000 32, 500 56, 000 39, 000 50,000 b 162, 000 167, 000 136, 100 149, 000 154, 000 c 206, 000 219, 500 215, 900 204,000 216, 000 Tensile Ultimate, Engineering,

p.s.i a 138, 000 144, 000 143, 800 178,000 180, 400 b 174, 000 204, 000 161, 000 195, 000 203, 400 c 231, 000 234, 000 230, 100 255,00 260, 000 Elongation, percent a 22 10.0 10.0 14. 1 10.0 b 7 3.0 3.0 3.0 4. 0 c 4 2. 0 1. 0 1. 0 l. 0 Reduction in Area, percent a 23 11.8 11.6 14.7 1 10. 0

b 21 5.0 7.9 4.2 5.7' c 8 5. 0 1. 6 1. 8 1.8 Charpy Impact, 40 E, it.-lbs a 14 13. 3 10.3 9. 7 8. 4 b 6 4. 4 6. 4 6. 4 8. 1 c 3 3.2 3. 4 4. 7 4. 4 Hardness, Rockwell C a 1 10 1 10 27 31 34 b 39 43 41 43 43 c 47 48 48 52 51 1 Approximated.

C (1 CODE TO THERMAL TREATMENT, TABLE III 0 e (a) In as solutionized condition. solutionized by heating to 1,600 F.1,800 F. soaking for 6 hrs, and water quenching. (b) solutionized and aged at 400 F.450 F. for 6-8 hours. (0) solutionized and aged at 550 F.600 F. for 6-8 hours.

It is to be concluded from the information in Tables II and III, for example, that maximum strength and hardness is exhibited by Composition C in the as extruded condition as shown in Table II, while maximum ductility and impact resistance are exhibited by Composition A in the as solutionized condition as shown in Table III, and highly desirable combinations of medium yield strength together with good impact resistance are exhibited by Compositions D and E in heat treated condition (b) from Table III. Thus, from the tables a choice is provided for selection of the most desirable properties by varying the content of the metals Within the narrow ranges provided and obtaining another choice of selecting the most desired property by utilizing anyone of the thermal treatments that have been utilized in compiling the data in the tables. The result is high density alloys with a certain amount of selectivity of the heretofore unattained mechanical properties.

The data herein was derived from experimental alloys which utilized uranium depleted in the U-235 isotope. However, since mechanical property characteristics are generally known and accepted to be independent of isotope, the disclosure is extended to also include uranium which contains the U-23S isotope in various amounts, such as that used for atomic energy purposes.

What is claimed is:

1. An alloy with a composition consisting of 93.5% to 96.5% by Weight of uranium, .752.0% molybdenum, .752.0% of columbium, .752.0% of zirconium and .25.50% of titanium.

2. An alloy with a composition consisting of 93.5- 96.5% by Weight of uranium depleted of the U-235 isotope, .752.0% of molybdenum, .752.0% of columbium, 1.752.0% of zirconium, .25.50% of titanium and incidental impurities not to exceed .1%.

3. An alloy with a composition consisting of 95% by weight of uranium, 1.25-1.75 each of columbium, molybdenum, zirconium and .25.50% titanium and exhibiting after extrusion maximum mechanical properties of strength and hardness.

4. An alloy with a composition consisting of 93.5% by weight of uranium, 1.75-2.25 each of molybdenum, columbium, zirconium and .25.5 0% titanium and exhibiting in as solutionized condition maximum mechanical properties of ductility and impact resistance.

References Cited by the Examiner Survey of Ternary and Quaternary Mestastable Gamma- Phase Uranium Alloys, July 15, 1958, pages 1 and 6.

BENJAMIN R. PAD GETI, Primary Examiner.

CARL D. QUARFORTH, REUBEN EPSTEIN, -L. DE'

55 WAYNE RUTLEDGE, Examiners.

M. J. SCOLNICK, Assistant Examiner. 

1. AN ALLOY WITH A COMPOSITION CONSISTING OF 93.5% TO 96.5% BY WEIGHT OF URANIUM, 75-2.0% MOLYBEDENUM, .75-2.0% OF COLUMBIUM, 75-2.0% OF ZIRCONIUM AND .25-.50% OF TITANIUM.
 4. AN ALLOY WITH A COMPOSITION CONSISTING OF 93.5% BY WEIGHT OF URANIUM, 1.75-2.25% EACH OF MOLYBDENUM, COLUMBIUM, ZIRCONIUM AND .25-50% TITANIUM AND EXHIBITING IN AS SOLUTIONIZED CONDITION MAXIUM MECHANICAL PROPERTIES OF DUCTILITY AND IMPACT RESISTANCE. 